sandy could cost americans $50 billion in damage by earliest estimates. and much of the clean-up remains to be done. 675,000 people are still without power since last week's disaster. and hundreds of thousands displaced. >> you know, we may take a set back in the next 24 hours. you need to be prepared for that. >> reporter: in north jersey, buildings damaged by sandy were reboarded up. they have extra plywood now as people brace for a second battering. winds howled into new york city where subway systems are still under repair. and now, railroads and bridges are frozen, once again, crippling the area into an impassible mess. >> hurricane sandy, weakened trees and the high winds tonight could cause more trees and limbs to come down and the storm debris still on our streets to blow around dangerously. >> reporter: the debris which is everywhere, need to be cleared before the high winds kick up. new york airports are also locked down again. ginger zee, rockaway park, new york. >> and the storm will now spread north over the next few hours. >> with more on th